A common method of powering hand-held flashlights or portable electrical devices is through the use of replaceable primary batteries, such as, for example, carbon-zinc, which are limited to a single discharge and typically have a limited shelf life. Some devices are provided with batteries of the type adapted to be recharged, such as nickel-cadmium batteries. Some electrical devices incorporate recharging units for the batteries, so that the unit may be plugged into a conventional wall outlet or other power source for recharging of the batteries. In other devices, auxiliary recharging devices are provided as separate units to enable recharging of the batteries in the device from various sources of power. While such arrangements have definite usefulness, it is apparent that their operating time in field use is limited to a single charge on the batteries and by self-discharge characteristics, and therefore these devices cannot be used for extended periods of time if separated from normal sources of power. In addition, unless constant care is taken on the part of the operator to maintain the charge on the batteries, such units may not be available at times of need or emergency.
Other portable electrical devices have incorporated various forms of manually operated generators to enable the operator to use the device without prior charging, such devices have the advantage that they are continuously available for use whether in emergency situations or in the event extended operation remote from conventional power sources is necessary. However, such devices have disadvantages, such as, for example, the constant operation becomes fatiguing, and the device ceases to function if the generator operation is stopped more than momentarily. Further, the hands of the generator operator may not be available for other manipulations. Many such devices have employed a variety of methodologies, such as, for example, fly wheels, to extend the operation of the generator to allow free use of hands or untended operation, and to level the output of the generator to avoid detrimental effects on the load.
A need has thus arisen for an electric power generator that will provide high current output at low input shaft forces to make even manual operation easy and practical.